1. Field of the Invention
This invention relates in general to managing workload within a computing system and in particular to managing workload in a logically partitioned system.
2. Description of the Related Art
Logically partitioned systems in which single physical machines are partitioned into multiple logical machines are well known in the art. Logical partitioning allows the establishment of a plurality of system images within a single physical machine or central processor complex (CPC). Each system image is capable of operating as if it were a separate computer system. That is, each logical partition can be independently reset, initially loaded with an operating system that may be different for each logical partition, and operate with different software programs using different input/output (I/O) devices.
Examples of logically partitioned computing systems are described in, for instance, U.S. Pat. No. 4,564,903 (Guyette et al.), entitled “Partitioned Multiprocessor Programming System”; U.S. Pat. No. 4,843,541 (Bean et al.), entitled “Logical Resource Partitioning of a Data Processing System”; and U.S. Pat. No. 5,564,040 (Kubala), entitled “Method and Apparatus for Providing a Server Function in a Logically Partitioned Hardware Machine”, each of which is incorporated herein by reference. Commercial embodiments of logically partitioned systems include, for example, IBM zSeries and System z9 (collectively, System z) systems and IBM POWER5-based systems. (POWER5, System z and System z9 are trademarks, and zSeries is a registered trademark, of IBM Corporation.)
One important aspect of a logically partitioned system is the management of workload running within the partitions of that system. In the industry there are a number of examples of workload managers which are used to manage the workload within and among the partitions. One such workload manager is the workload manager in the z/OS operating system. (z/OS is a registered trademark of IBM Corporation.) In general these workload managers attempt to balance the workload of the partitions by moving work to the physical resources of the system. In order to move the work, however, it is important to ensure that the data needed by the relocated work is at the moved location. This need often restricts the movement of work.
The z/OS workload manager improved on this capability by providing the capability of moving central processor unit (CPU) capacity between logical partitions. This capability is described in U.S. Pat. No. 6,587,938, incorporated herein by reference. This z/OS workload manager, however, uses a peer-to-peer management approach where the workload management function on each partition has full knowledge of the workload running on each of the other partitions being managed. This requires a large amount of data to be shared between the partitions. To do this data sharing in an efficient manner, the z/OS workload manager depends on each partition being managed having access to a mechanism to share memory across the partitions. Such memory-sharing capability is not available in all logically partitioned environments, limiting the applicability of the z/OS approach.